While buying Tumblr isn’t necessarily a bad deal for the two companies, as my colleague Mathew Ingram wrote, there’s another photo site out there that might have been an even better deal: Pinterest.

In many ways, Pinterest is also building a mobile-friendly photo site just like Tumblr, but Pinterest is also in the midst of constructing the underpinnings for a potentially much more lucrative native revenue experience. Pinterest is oriented around commerce and consumers craving particular items. That’s good for business.

No, buying Pinterest wouldn’t help Yahoo discover its inner tween. It’s a well-known fact that Pinterest is populated mainly by adult women — not exactly the demographic Yahoo needs to attract. And no, considering Pinterest’s valuation as of its last funding round, such an acquisition probably wouldn’t have come cheap. Acquiring the company would require a much bigger departure from Yahoo’s current mass-market advertising into the world of e-commerce and affliate links. It could be a harder sell to the company’s investors, and a bigger transition for everyone.

But if Yahoo is looking to shell out the big bucks for a site with viral growth, visuals to compete with Facebook, and a devoted community of users, Pinterest might have been the better choice. According to a Pew report in December, out of all online adults (which is basically anyone with an internet connection), just six percent of those people visited Tumblr on a regular basis, compared with 13 percent on Instagram (which isn’t exactly for sale), and 15 percent on Pinterest — only Twitter comes in at 16 percent ahead of the others and behind behemoth Facebook at 67 percent.

Less than a year out of beta, Pinterest is a dominant force on the web; a place where women of all ages collect photos of things that inspire them or things that they want to remember or create. For many, it’s a digital wish-list. And because of that, Pinterest sends huge amounts of traffic to online retailers. To be the intermediary between the people and the stores is a good place to be — you’re a crucial link that drives the sales, without any of the hassle of shipping or orders or user acquisitions that come with e-commerce.

Pinterest CEO Ben Silbermann at the company’s new offices in San Francisco.

Pinterest has no business model in place right now — the site is free to join and for brands to integrate with — but that’s just right now, and it likely won’t last. The company just announced yesterday that it is starting to connect photos of items back to the brands who sell them, and it’s not hard to image how this could play out.

Tumblr does have a business model right now based on ads, and it just started rolling them out on mobile users in April. But the company has been reportedly burning through cash and not yet making a lot of revenue, hoping to bring in $100 million this year. But people are usually pretty unhappy about a free product suddenly peppering them with ads — especially if those ads are dropped into a feed that users have created (just ask anyone how they feel about Facebook ads.) CEO David Karp said at our paidContent event just last month that he wants advertising on the site to be native and unobstrusive.

“We focused on higher up in the funnel, the type of advertising that creates intent,” Karp told us in April. “It gives room for the most creative advertisers to create their best work. I think we’ve started to prove it, and see really good examples of it.”

Suddenly, the possible Pinterest model of taking a cut on sales and traffic resulting from users creating digital shopping lists looks a lot less disruptive to the core experience, and potentially more lucrative, than trying to solve mobile display ads for the Tumblr feed. Making money off traffic and sales wouldn’t disrupt Pinterest’s core product, and would generally fit in with the company’s existing user experience, just as promoted tweets are fitting with Twitter’s on both desktop and mobile (a profitable venture so far estimated to bring Twitter $528 million in ad revenue this year.)

So no, buying Pinterest wouldn’t make Yahoo all that hip. But buying the site that has potential to become a strong force in modern, social retail? Seems like a good bet — especially since teens might leave you once Mom joins and you become mainstream.